Water: Coastal Zone Act Reauthorization Amendments
J. Wetlands Forest Management
Plan, operate, and manage normal, ongoing forestry activities (including harvesting, road design and construction, site preparation and regeneration, and chemical management) to adequately protect the aquatic functions of forested wetlands.
This management measure is intended for forested wetlands where silvicultural or forestry operations are planned or conducted. It is intended to apply specifically to forest management activities in forested wetlands and to supplement the previous management measures by addressing the operational circumstances and management practices appropriate for forested wetlands. Chapter 7 provides additional information on wetlands and wetland management measures for other, nonforestry source categories and activities.
Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal nonpoint source programs in conformity with this measure and will have some flexibility in doing so. The application of this management measure by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce.
This management measure applies specifically to forest management activities in forested wetlands, including those currently undertaken under the exemptions of section 404(f) (40 CFR, Part 232). Many normal, ongoing forestry activities are exempt under section 404(f)(1) unless recaptured under the provisions of section 404(f)(2). This management measure is not intended to prohibit these silvicultural activities but to reduce incidental or indirect effects on aquatic functions as a result of these activities. Chapter 7 provides additional information on wetlands and wetland management measures for other, nonforestry source categories and activities.
Forested wetlands provide many beneficial functions that need to be protected. Among these are floodflow alteration, sediment trapping, nutrient retention and removal, provision of important habitat for fish and wildlife, and provision of timber products (Clairain and Kleiss, 1989). The extent of palustrine (forested) wetlands in the continental United States has declined greatly in the past 40 years due to conversion to other land uses, with a net annual loss of 300,000 acres occurring between 1950 and 1970 (Frayer et al., 1983). Forested wetland productivity is dependent upon hydrologic conditions and nutrient cycling, and alteration of a wetland's hydrologic or nutrient-cycling processes can adversely affect wetland functions (Conner and Day, 1989). Refer to Chapter 7 for a wetland definition and a more complete description of the values and functions of wetlands.
The primary difference between forestry activities on wetland sites as compared to activities on upland sites is the result of flooding that occurs in most wetlands during some or most of the year. Potential impacts of forestry operations in wetlands include:
- Sediment production as a result of road construction and use and equipment operation;
- Drainage alteration as a result of improper road construction;
- Stream obstruction caused by failure to remove logging debris;
- Soil compaction caused by operation of logging vehicles during flooding periods or wet weather (skid trails, haul roads, and log landings are areas where compaction is most severe); and
- Contamination from improper application and/or use of pesticides.
The primary adverse impacts associated with road construction in forested wetlands are alteration of drainage and flow patterns, increased erosion and sedimentation, habitat degradation, and damage to existing timber stands. In an effort to prevent these adverse effects, section 404 of the Federal Water Pollution Control Act requires usage of appropriate BMPs for road construction and maintenance in wetlands so that flow and circulation patterns and chemical and biological characteristics are not impaired. Additional section 404(f) BMPs specific to forestry can be found at 40 CFR 232.3.
Harvest planning and selection of the right harvest system are essential in achieving the management objectives of timber production, ensuring stand establishment, and avoiding adverse impacts to water quality and wetland habitat. The potential impacts of reproduction methods and cutting practices on wetlands include changes in water quality, temperature, nutrient cycling, and aquatic habitat (Toliver and Jackson, 1989). Streams can also become blocked with logging debris if SMAs are not properly maintained or if appropriate practices are not employed in SMAs.
Site preparation includes but is not limited to the use of prescribed fire, chemical, or mechanical site preparation. Extensive site preparation on bottoms where frequent flooding occurs can cause excessive erosion and stream siltation. The degree of acceptable site preparation is governed by the amount and frequency of flooding, soil type, and species suitability, and is dependent upon the regeneration method used.
Clean Water Act section 404 establishes a permit program that regulates the discharge of dredged or fill material into waters of the United States, including certain forested areas that meet the criteria for wetlands. Section 404(f)(1) of the Act provides an exemption from the permitting requirement for discharges in waters of the United States associated with normal, ongoing silviculture operations, including such practices as placement of bedding, cultivation, seeding, timber harvesting, and minor drainage. Section 404(f)(2) clarifies that discharges associated with silviculture activities identified at 404(f)(1) as exempt, are not eligible for the exemption if the proposed discharge involves toxic materials or if they would have the effect of converting waters of the United States, including wetlands, to dry land. Regulations implementing section 404(f), as well as describing applicable best management practices for avoiding impairment of the physical, chemical, and biological characteristics of the waters of the United States, were promulgated by EPA at 40 CFR Part 232.
3. Management Measure Selection
Mader and others (1989) assessed the relative impacts of various timber harvesting methods on different parameters in a forested wetland. On-site ecological responses on a clearcut site following timber harvesting with helicopter and rubber-tired skidder systems were compared to a clearcut, harvested, herbicide-treated area and an undisturbed stand in southwest Alabama. They found total nitrogen concentrations in soil water to be significantly lower for the skidder treatment when compared with all other treatments (Table 3-63). Total phosphorus concentrations were also significantly different for the helicopter treatment as compared to the control stand. Sediment accumulation was greatest for the helicopter treatment and least for the herbicide treatment, and all differences between treatments were significant.
As discussed more fully at the beginning of this chapter and in Chapter 1, the following practices are described for illustrative purposes only. State programs need not require implementation of these practices. However, as apractical matter, EPA anticipates that the management measure set forth above generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices set forth below have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measure described above.
a. Road Design and Construction Practices
- Locate and construct forest roads according to preharvest planning.
Improperly constructed and located forest roads may cause changes in hydrology, accelerate erosion, reduce or degrade fisheries habitat, and destroy or damage existing stands of timber.
- Utilize temporary roads in forested wetlands.
Permanent roads should be constructed only to serve large and frequently used areas, as approaches to watercourse crossings, or as access for fire protection. Use the minimum design standard necessary for reasonable safety and the anticipated traffic volume.
- Construct fill roads only when absolutely necessary for access since fill roads have the potential to restrict natural flow patterns.
Where construction of fill roads is necessary, use a permeable fill material (such as gravel or crushed rock) for at least the first layer of fill. The use of pervious materials maintains the natural flow regimes of subsurface water. Figures 3-28 and 3-29 demonstrate the impact of impervious and pervious road fills on wetland hydrology. Permeable fill material is not a substitute for using bridges where needed, or for installation of adequately spaced culverts present at all natural drainageways. This practice should be used in conjunction with cross drainage structures to ensure that natural wetland flows are maintained (i.e., so that fill does not become clogged by sediment and obstruct flows (Hynson et al., 1982).
- Provide adequate cross drainage to maintain the natural surface and subsurface flow of the wetland.
This can be accomplished through adequate sizing and spacing of water crossing structures, proper choice of the type of crossing structure, and installation of drainage structures at a depth adequate to pass subsurface flow. Bridges, culverts, and other structures should not perceptibly diminish or increase the duration, direction, or magnitude of minimum, peak, or mean flow of water on either side of the structure (Hynson et al., 1982).
- Construct roads at natural ground level to minimize the potential to restrict flowing water.
Float the access road fill on the natural root mat. If the consequences of the natural root mat failing are serious, use reinforcement materials such as geotextile fabric, geo-grid mats, or log corduroy. Figure 3-30 depicts a cross section of the "floating the road" practice. Protect the root mat beneath the roadway from equipment damage. This can be facilitated by diverting through traffic to the edge of the right-of-way, shear-blading stumps instead of grubbing, and using special wide-pad equipment. Also, protect the root mat from damage or puncture by using fill material that does not contain large rocks or boulders.
b. Harvesting Practices
- Conduct forest harvesting according to preharvest planning designs and locations.
Planning and close supervision of harvesting operations are needed to protect site integrity and enhance regeneration. Harvesting without regard to season, soil type, or type of equipment can damage the site productivity; retard regeneration; cause excessive rutting, churning, and puddling of saturated soils; and increase erosion and siltation of streams.
- Establish a streamside management area adjacent to natural perennial streams, lakes, ponds, and other standing water in the forested wetland following the components of the SMA management measure.
- Ensure that planned harvest activities or chemical use do not contribute to problems of cumulative effects in watersheds of concern.
- Select the harvesting method to minimize soil disturbance and hydrologic impacts to the wetland.
In seasonally flooded wetlands, a guideline is to use conventional skidder logging that employs equipment with low-ground-pressure tires, cable logging, or aerial logging (Doolittle, 1990). Willingham (1989) compared cable logging to helicopter logging and concluded that helicopter operations caused less site disturbance, were more economical, and provided greater yield. Table 3-64 depicts harvesting systems recommended by the Florida Division of Forestry by type of forested wetland. These recommendations are based on both water quality and economic considerations. Another alternative is to conduct harvesting during winter months when the ground is frozen.
- When groundskidding, use low-ground-pressure tires or tracked machines and concentrate skidding to a few primary skid trails to minimize site disturbance, soil compaction, and rutting.
- When soils become saturated, suspend groundskidding harvesting operations. Use of groundskidding equipment during excessively wet periods may result in unnecessary site disturbance and equipment damage.
c. Site Preparation and Regeneration Practices
- Select a regeneration method that meets the site characteristics and management objectives.
Choice of regeneration method has a major influence on the stand composition and structure and on the silvicultural practices that will be applied over the life of the stand (Toliver and Jackson, 1989). Natural regeneration may be achieved by clearcutting the existing stand and relying on regeneration from seed from adjacent stands, the cut trees, or stumps and from root sprouts (coppice). Successful regeneration depends on recognizing the site type and its characteristics; evaluating the stocking and species composition in relation to stand age and site capability; planning regeneration options; and using sound harvesting methods. Schedule harvest during the dormant season to take advantage of seed sources and to favor coppice regeneration. Harvest trees at a stump height of 12 inches or less when practical to encourage vigorous coppice regeneration. Artificial regeneration may be accomplished by planting seedlings or direct seeding. Table 3-65 contains the regeneration system recommendations of the Georgia Forestry Association.
- Conduct mechanized site preparation and planting sloping areas on the contour.
- To reduce disturbance, conduct bedding operations in high-water-table areas during dry periods of the year.
The degree of acceptable site preparation depends on the amount and frequency of flooding, the soil type, and the species suitability.
- Minimize soil degradation by limiting operations on saturated soils.
d. Chemical Management Practices
- Apply herbicides by injection or application in pellet form to individual stems.
- For chemical and aerial fertilizer applications, maintain and mark a buffer area of at least 50 feet around all surface water to avoid drift or accidental direct application.
Avoid application of pesticides with high toxicity to aquatic life, especially aerial applications.
- Apply slow-release fertilizers, when possible.
This practice will reduce the potential of the nutrients leaching to ground water, and it will increase the availability of nutrients for plant uptake.
- Apply fertilizers during maximum plant uptake periods to minimize leaching.
- Base fertilizer type and application rate on soil and/or foliar analysis.
To determine fertilizer formulations, it is best to compare available nitrogen, phosphorus, potassium, and sulphur in the soils to be treated with the requirements of the species to be sown.